Hypophosphatemia After Intravenous Ferric Carboxymaltose in Heart Transplant Patients

Abstract

<h3>Purpose</h3> Iron deficiency and iron deficiency anemia are both comorbidities potentially occurring in patients with heart failure (HF) and in patients undergoing heart transplantation (HT), that could increase morbility and mortality. Intravenous administration of ferric carboxymaltose (FCM) is related with hypophosphatemia (HPP). However, adverse effects in solid organ transplant population have been scarcely studied. Here we assessed the incidence of HPP in HT patients. Secondary outcome compares the PPH rate between these patients and those with HF after FCM. <h3>Methods</h3> This is a single-center, retrospective study conducted in a tertiary care center. All patients with HF or HT who received FCM between Sept'2015 and Sept'2017 were included. Demographics, pathology under study and comorbidities and immunosuppressants were collected from medical records. Blood and biochemical parameters: hemoglobin, sodium, potassium, calcium, phosphate, creatinine, ferritin, transferrin saturation, hepatic enzymes and albumin were gathered from laboratory tests taken before and after FCM administration. HPP was established as a blood phosphate concentration < 0.85 mmol/L. Quantitative variables are presented as median and interquartile range, qualitative variables as n (%). Differences between groups were determined using the Chi-square test for qualitative variables and the Student's t-test for quantitative variables. <h3>Results</h3> During this period 223 patients received FCM (17.5% HT). Among the 39 HT patients, 10 (25.64%) developed HPP, in contrast to the HF group, where HPP was found in 9 out of 184 patients (4.89%) (p= 0.0002). After FCM, phosphate was significantly lower in HT group than in HF group (0.58mmol/L [0.45-0.69] and 0.74mmol/L [0.68-0.80]) respectively, p=0.014). 3 patients with HT patients required exogenous phosphate treatment: 1 orally and 2 intravenously, either because of symptoms or because of phosphate concentration < 0.5 mmol/L. <h3>Conclusion</h3> Despite our low sample, incidence of HPP after FCM was higher in patients undergoing HT than in patients with HF. In addition, this HPP tended to be more severe in the HT group. Because both FCM and immunosuppressants may cause HPP as a common side effect, the combination of both drugs may synergize. Further research is needed to determine variables that influence serum phosphate depletion after FCM administration in HT patients.